Robert w



(No Model.)

R. W.I AITKBN.

STEAMA BOILER.

Patented June 22, 18861 N. PETERS rmsouxhogmpher. wmmgm. n. c.

UNITED STATES PATENT runen.

ROBERT W. AITKRN, or BUFFALO, NRW YORK, AssIeNOR OF ONEHALF TO THE rrTTs AGRICULTURAL WORKS, oir SAME PLAGE.

STEAM-BOILER.

SPECIFICATION forming part of Letters Patent No. 344,071, dated June 22, 1886.

Application tiled September l, 1885.

To'aZZ whom, it may concer-71,;

Be it known that I, ROBERT W. AITKEN, of the city of Buffalo, in the county of Erie and State of New York, have invented new and useful Improvementsin Steam-Boilers, of

which the following is a specification.

This invention relates to an improvement in that class of steamboilers which are provided with a direct Viiue extending from the fire-box 1o to a combilstion-chamber at the rear end of the boiler, and with a number of return-dues running from said combustion-chamber to a smoke-box at the front end of the boiler.

The object of my invention is to improve the construction of the iirebox in such 1nan 2o improvements which will be hereinafter fully set forth, and pointed out in the claim.

In the accompanying drawings, Figure l is a longitudinal sectional elevation of the iirebox and adjacent parts of a steam-boiler provided with my improvements. Fig. 2 is a cross-section in line x x, Fig. 1. Fig. 3 is a similar view on a reduced scale, showing a slightly-modified form of the fire-box.

Like letters of reference refer to like paris 3o in the several figures.

A represents the cylindrical boiler, B the fire-box, and C the water-jacket surrounding the re-box.

D represents the direct iiue, extending from the upper portion of the flue-sheet d of the nre-box in a well-known manner to the combustion-chamber' at the opposite endof the boiler, which is not shown in the drawings.

Serial No. 175,937. (No model.)

E represents the return-fines, which are arranged in the shell A on both sides of the di- 4o rect ilue D, and which extend beyond the firebox to the flue-sheet c, through which they open into a suitable smokebox. The side plates of the fire-box are composed of lower vertical portions, f, and upper contracted or converging portions, f. The crown-sheetfz, connecting the upper ends of the contracted portions f', is made concentric with the direct flue D. This construction of the side walls of the hre-box permits the returirflues E to be arranged lower in the shell A on both sides of the iiue D than ordinarily, thereby increasing the heating-surface of the returntlues and decreasing the height of the waterlevel above the lues, whereby steam is made more rapidly than heretofore. This construction also enables the grate G to be raised and lowered in the fire-box, thereby permitting the grate to be placed low for burning straw, as indicated in full lines, or higher for burning coal, as indicated in dotted lines.

I claim as my invention- In a steam-boiler, the combination, with the direct fine D and return-fines E, of a iire-box having its side walls composed of' lower vertical portions, f, and upper converging portions, f', and having a erOwn-sheet,f, made concentric with the direct ilue D, substantially as set forth.

. fitness my hand this Sth day ot' August, 7o 1885. f

ROBERT V. ATTKEN.

Vitnesses:

O. H. KROTZ, THEO. L. Porr. 

